To provide a water purifier allowing the replacement of the two filters, a pre-processing filter and a post-processing filter, at the same time.

In a water purifier where raw water is supplied into a cartridge housing, then it is purified at water purification layer parts V1, V2 after being subjected to the primary filtration by a pretreatment filter 30A, and subsequently the purified water is discharged after being subjected to the secondary filtration by a post-treatment filter 30B, a cylindrical filter guide 15 is installed in the cartridge housing 10, the water purification layer parts V1, V2 are formed between the cartridge housing and the cylindrical filter guide 15, and a filter housing 25 accommodating the two filters separately is detachably mounted.